Fumigation apparatus

ABSTRACT

As shown in FIG.  1  there is one embodiment of a fumigation apparatus in the form of a module ( 8 ) including a panel ( 10 ) which can be positioned in or at an opening of an enclosed space in use to define a fumigation chamber. Fumigant inlet means in the form of an orifice ( 12 ) are arranged in the panel ( 10 ) to allow a flow of a fumigant directly into the fumigation chamber. A nominal number of mixing fans, in this case two fans ( 16 ) and ( 18 ), thoroughly circulate gases within the fumigation chamber when operating. The module ( 8 ) includes a system control box ( 14 ) linked to the fumigant delivery orifice ( 12 ) and valve system which functions to control the flow of toxic gas into the fumigation chamber. The panel ( 10 ), when positioned in use, is secure against the passage of fumigant and gases by means of an inflatable rubber seal ( 22 ) which is located around a lip edge perimeter of the panel ( 10 ). Extraction means for evacuation of the fumigation chamber gases includes a pipe ( 28 ) attached to an orifice ( 30 ) located in the lower region of the panel ( 10 ), the pipe ( 28 ) in turn connected to a contra-rotating fan ( 34 ) and an actuated butterfly valve ( 32 ) and thence to a pipe exhaust stack ( 36 ). Absorption means are operatively coupled to the extraction means on the module ( 8 ) to absorb at least part of the fumigant extracted from the fumigation chamber. The absorption means is in the form of a removable absorption bed cartridge ( 40 ) and includes activated carbon to which the fumigant attaches or is absorbed and is thus stripped from the gas/fumigant extracted from the fumigation chamber.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. Ser. No.10/332,602, filed on Jan. 10, 2003, the filing priority of which isclaimed and the entire disclosure of which is hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates generally to a fumigation apparatus. Theinvention will primarily be described with reference to its use toprovide fumigation of grains and other agricultural products, but itshould be realized that the invention can have broader applications toany other bulk materials, goods or produce which may contain pests orinsects or other vermin and which therefore require fumigation.

BACKGROUND TO THE INVENTION

Many crops, grains and other agricultural products contain pests,parasites, insects or other vermin, such as for example borers, lice,ticks, fleas or termites. It is best to treat such bulk materials insitu so that multiple handling in a further treatment process is notrequired and before the goods leave their geographic region of origin toprevent the spread of insects and vermin.

Fumigation devices for bulk materials are known in the art that involveplacement of a heavy, impervious blanket or other covering article overthe materials followed by subsequent addition of toxic gas flow underthe blanket to fumigate the covered goods. Current methods of fumigationunder blankets are crude, ineffective at fully eliminating insectinfestation since no mixing of gases with bulk materials can occur, andhighly dangerous from an occupational health standpoint since the gasesused for effective fumigation are extremely toxic. Atmosphericdischarges of fumigant gases such as methyl bromide are highlyundesirable also because this gas is an ozone depleting substance.

In JP2303442 a fumigation system is described which teaches venting thegaseous fumigant (or incinerating and then venting to atmosphere thegaseous products of the so-incinerated fumigant) once it has beenexhausted or extracted from a fumigation chamber. This document teachesthat the way to deal with fumigant or fumigant by-products is by ventingto atmosphere, whether by fan extractor located on the fumigationcontainer or coupled to such a device on an adjacent mobile vehicle.Once again such atmospheric discharges are undesirable from a pollutionand occupational health standpoint.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided afumigation module for fumigation of a fumigation chamber adapted tocontain produce, the module including:

a panel which is adapted to be directly mounted and removably positionedin or at an opening of the fumigation chamber;

fumigant inlet means operatively coupled to the panel to allow a flow ofa fumigant into the fumigation chamber;

extraction means also being operatively coupled to the panel to remove amajority of the fumigant from the fumigation chamber; and

absorption means operatively coupled to the extraction means, theabsorption means being designed to absorb substantially all of thefumigant extracted from the fumigation chamber.

Advantageously the present fumigation chamber venting system permitsfumigant to be absorbed during the extraction step without allowingfumigant or fumigant by-products to escape to atmosphere.

In a second aspect the invention also provides a fumigation assemblyincluding the module of the first aspect and a fumigation chamberadapted to contain produce having a rigid support structure. Typicallythis structure can comprise a silo, shed, warehouse or the like whichhas at least a rigid frame.

Preferably the fumigation module of the first or second aspects furthercomprises control means operatively coupled to the module and arrangedto control the flow of fumigant into the fumigation chamber.

Preferably the control means includes a system control box and a systemof fumigant delivery pipes and valves adapted in use to supply fumigantfrom a supply source to the fumigation chamber.

Preferably the absorption means comprises an absorption bed includingactivated carbon to which at least part of the extracted fumigantattaches.

Preferably the module is adapted to be attached to a source of thefumigant which is directly associated with a heating source, the latterused to convert the fumigant into a gaseous form. The heat energytransferred to the fumigant should be such that it becomes more buoyantthan ambient air.

Preferably the fumigant inlet means is adapted to detachably couple to amobile source of the fumigant such as a motor vehicle on which afumigant vessel is mounted.

Preferably the fumigant inlet means includes a dispersion pipe system inuse located above the contents of the fumigation chamber. Such anarrangement allows the fumigant, which is generally heavier than air, tofall in a dispersed fashion downward over the top of the produce whichhas been loaded into the fumigation chamber.

Preferably the panel when positioned in use is secure against thepassage of fumigant and is fitted with external locking cam devicesadapted to be secured, for example, with a spring-loaded cliparrangement.

Preferably the panel when positioned in use is secure against thepassage of fumigant and gases by an inflatable seal which can beinflated for example by means of a compressor fitted to the module. Thismeans that toxic gases from the process in the fumigation chamber willnot pose any occupational health risk to operators of the fumigationapparatus during processing, while they may be standing alongside thepanel.

Preferably the module is provided with a plurality of mixing fansadapted to circulate fumigant and gases within the fumigation chamber.Such an arrangement allows more even and thorough dispersion of thefumigant and gases as they enter and are dispersed in the fumigationchamber.

Preferably the extraction means includes a pipe attached to an orificelocated in a lower region of the panel, the pipe being connected in turnto an actuated butterfly valve further connected in turn to acontra-rotating fan adapted to provide suction for the extraction of thefumigant. More preferably the extraction means includes an exhaust stackpositioned vertically above the module, the uppermost terminal of theexhaust stack being fitted with a gas diffuser and appropriate rainguard, and the exhaust stack being arranged to receive the extractedgases which are stripped of fumigant.

Preferably the module is fitted with a plurality of small diameter pipesindependently connected via an arrangement of taps and connectors to afumigant sampling and detection meter unit located at the module.

Preferably the module includes a fumigant sampling and detection meterunit and power supply switches for mixing fans, exhaust fan and valveactuators.

In a further preferred embodiment the module is provided in two portionsadapted to be operatively coupled together. Preferably a first portionincludes the fumigant inlet means and a second portion includes thefumigant extraction and absorption means.

In either of the preferred embodiments of the invention the fumigationmodule is constructed as a rectangular panel with a protruding frame onthe exterior face so that the panel can stand independently upright.Effective fumigation of produce by skilled operators would allow for thesafe treatment of material in situ and may eliminate the possibility ofinsects or vermin escaping into the environment, or being transportedacross the country in contaminated produce. This invention can provide afaster fumigation processing rate than the present technology along withenhanced health and safety benefits.

According to a third aspect of the present invention there is provided amethod of fumigating produce including the steps of:

providing a fumigation module which includes a panel, the panel adaptedto removably attach to a fumigation chamber, with fumigant inlet,extraction and absorption means being operatively coupled to the panel;

locating the produce to be fumigated in the fumigation chamber;

directly attaching the panel in or at an opening of the fumigationchamber;

providing a flow of a fumigant to the fumigation chamber via thefumigant inlet means; extracting a majority of the fumigant from thechamber via the fumigant extraction means; and

absorbing substantially all of the extracted fumigant using theabsorption means.

According to a fourth aspect of the present invention there is provideda method of fumigating produce including the steps of:

providing a fumigation apparatus including a first portion of a moduleincluding a panel, the panel adapted to removably attach to a fumigationchamber, with fumigant inlet means being operatively coupled to thepanel;

locating the produce to be fumigated in the fumigation chamber;

directly attaching the panel in or at an opening of the fumigationchamber;

providing a flow of a fumigant to the fumigation chamber via thefumigant inlet means;

providing a second portion of the module adapted to removably attach tothe panel, with fumigant extraction and absorption means beingoperatively coupled to the second portion;

extracting a majority of the fumigant from the chamber via the fumigantextraction means; and

absorbing substantially all of the extracted fumigant using theabsorption means.

Preferably the fumigant extracted from the chamber is absorbed on anabsorption bed.

Preferably in either the third or the fourth aspects the method furthercomprises washing at least part of the absorption bed to remove theabsorbed fumigant.

Typically the absorption bed is washed with a scrubbing solution, suchas sodium thiosulphate, to yield one or more salts, such as bromide andsodium methylthiosulphate.

Generally the fumigant includes an alkyl halide such as methyl bromide.

In an embodiment of either the third or fourth aspects, the methodfurther comprises incinerating at least part of the absorption means,for example the absorption bed, and the fumigant absorbed thereto.

In an embodiment of either the third or fourth aspects, the methodfurther comprises desorbing the fumigant, for example by thermaldesorption, from at least part of the absorption means, for example theabsorption bed.

In an embodiment of either the third or fourth aspects, the methodfurther comprises disposing of at least part of the absorption means,for example the absorption bed, and the fumigant absorbed thereto.

In an embodiment of either the third or fourth aspects, the methodfurther comprises chemical destruction of the fumigant, for example byoxidation. The absorption means may comprise water.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within its scope,preferred forms of the invention will now be described, by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 shows a perspective schematic view of a fumigation apparatus inaccordance with one embodiment of the invention.

FIG. 1 a shows a perspective schematic view of a portion of theapparatus shown in FIG. 1.

FIG. 1 b shows a perspective schematic view of a portion of theapparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an embodiment of a fumigation apparatus in the form of amodule 8 which can be positioned in or at an opening of an enclosedspace in use to define a fumigation chamber. Typical enclosed spaces caninclude silos, sheds, warehouses and rooms of any dimension capable ofbeing sealed in a gas tight fashion. A typical opening into the enclosedspace could be a doorway, window, inspection port or custom fashionedportal to accommodate the module 8. Typically the opening or portal isof equivalent size to the panel 10 which forms a full side of the module8. The panel 10 in use then blocks the opening to the enclosed space.

A fumigant inlet means in the form of an orifice 12 is arranged in thepanel 10 to allow a flow of a fumigant directly into the fumigationchamber. An external source of gas provides heavy toxic gas molecules,for example methyl bromide, which have been appropriately heated,gasified and dispersed in air for transfer into the fumigation chamber.The heating source is used to convert the fumigant into a gaseous form.The heat energy transferred to the fumigant should be such that itbecomes more buoyant than ambient air. The orifice 12 is adapted to bedetachably coupled to a mobile source of the fumigant gas such as amotor vehicle on which a fumigant source vessel is mounted with theappropriate heating facilities thereat. The orifice 12 can be fittedwith suitable hose couplings or fittings to enable linkage with externalsources of gas.

A nominal number of mixing fans, in this case two fans 16, 18,thoroughly circulate gases within the fumigation chamber when operating.The mixing fans 16, 18 are located by appropriate wall mountings on theface of the panel 10 directed toward the interior of the fumigationchamber in use, to provide sufficient circulation to prevent the heavierthan air toxic gases from only locating in the lower portion of thefumigation chamber.

The module 8 includes a system control box 14 positioned at the panel 10and linked to the fumigant delivery orifice 12 and associated valvesystem. The system control box 14 functions to control the flow of toxicgas into the fumigation chamber. Such an arrangement ensures that at alltimes the availability of fumigation gases is able to be manuallycontrolled which ensures that highly safe operating procedures can bemaintained. A fumigant delivery pipe in the form of a perforated plasticdispersion pipe 20 is shown connected to the orifice 12, pipe 20 beingfor positioning above the produce in the fumigation chamber. Such anarrangement allows the fumigant, which is generally heavier than air, tofall in a dispersed fashion downward over the top of the produce whichhas been loaded into the fumigation chamber.

The panel 10 when positioned in use is secured against the passage offumigant and gases by means of an inflatable rubber seal 22 which islocated around a lip edge perimeter of the panel 10. When the panel 10is positioned in or at the opening to the enclosed space and immediatelyprior to use, the seal 22 is inflated by means of a compressor 24 fittedto the module 8. This means that toxic gases from the fumigation chamberwill not pose any occupational health risk to operators of thefumigation apparatus during processing, while they may be standingalongside the module 8. As shown in FIGS. 1 a and 1 b, the panel 10 isfitted with external corner locking cam devices 25 which enable thepanel 10 to be secured to the adjacent wall, for example by means of aspring loaded clip arrangement 26.

Extraction means for evacuation of the fumigation chamber gases includesa pipe 28 attached to an orifice 30 located in the lower region of thepanel 10, the pipe 28 in turn connected to an actuated butterfly valve32 and a contra-rotating fan 34 and thence to a pipe exhaust stack 36.The uppermost terminal of the stack 36 is fitted with a gas diffuser andappropriate rain guard 38. Control of the actuated butterfly valve 32and contra-rotating fan 34 are by means of system control box 14. Suchan arrangement allows the toxic, heavier than air gases to be removed byfan induced suction from the fumigation chamber at an appropriate lowerheight, where said gas molecules will naturally congregate withoutrecirculation, followed by dispersion to the external atmosphere via astack 36 which is of sufficient height to allow the gas contents of thefumigation chamber to be safely vented without occupational health riskexposure to operators or others located nearby the fumigation apparatus.The extraction fan can be of any suitable type, and not necessarilycontra-rotating, for example a centrifugal fan is also suitable.

Absorption means are operatively coupled to the extraction means toabsorb the majority of the fumigant extracted from the fumigationchamber. The absorption means is in the form of a removable absorptionbed cartridge 40 is located in pipe 28 downstream of the valve 32 andincludes activated carbon to which the fumigant (in one example beingmethyl bromide) is attached or absorbed, and is thus stripped from thegas/fumigant extracted from the fumigation chamber. The use of aplurality of in-line absorption cartridges is within the scope of theinvention.

A plurality of flexible plastic gas sampling lines are mounted on thepanel 10 at orifices 42 and independently connected via an appropriatesystem of pipes and connectors to a gas flow meter test unit locatedwithin system control box 14. Such an arrangement provides a gassampling system which draws small amounts of the gaseous contents of thefumigation chamber and delivers a reading on the gas flow meter testunit as to the concentration of toxic gas remaining in the fumigationchamber during the venting procedure. This monitoring is carried out toensure that the panel 10 may be safely disengaged from the fumigationchamber for the purposes of removing the charged produce withoutoccupational health risk exposure to operators or others located nearbythe module 8.

The system control box 14 also includes power supply switches andcircuits for operating the mixing fans 16, 18 and, as stated earlier,the actuated butterfly valve 32 and the contra-rotating fan 34. Such anarrangement provides a central and securable location for allelectrically operated devices, which is important when sequentialoperational steps are required.

In the preferred embodiment of the invention the module includes arectangular panel 10 with a protruding frame 44 on the exterior face sothat the panel 10 can stand independently upright when not in positionon or at an opening of the space to be enclosed. Other shapes of framesto enable safe placement of the module when disengaged from the enclosedspace would be within the scope of the invention, for example a panelhaving protruding legs or a basal wing on one side, or collapsiblesupport legs which can be outwardly oriented to the panel etc.

During use, produce for fumigation is loaded into the fumigation chambervia the opening or another gas tight doorway to provide access for theload. The module 8 is then moved so that the panel 10 is then sealedinto place at the opening and heated toxic gases, generated by warmingliquified fumigation reagent by means of a heating source, directlyenter the fumigation chamber via the orifice 12 and the pipe 20. Thesystem control box 14 functions to control the flow of toxic gas intothe fumigation chamber. The mixing fans 16, 18 circulate gases withinthe fumigation chamber when in use to provide good mixing of toxic gaseswith the charged material. When the fumigation interval is complete, therecirculation fans 16, 18 are switched off, the flow of toxic gas intothe chamber is stopped and gas is evacuated from the fumigation chamber,flowing consecutively through orifice 30, pipe 28, absorption cartridge40, contra-rotating fan 34 and actuated butterfly valve 32 beforeexiting the apparatus via pipe exhaust stack 36. As a safety check ofthe concentration of toxic gases remaining in the fumigation chamber,gas samples are drawn via a plurality of gas sampling lines connected toorifices 42 in panel 10 to a gas flow meter test unit located within thesystem control box 14 and a readout is obtained so that the operator mayascertain when it is safe to disengage panel 10 and move the module 8aside to access the produce after fumigation.

The methyl bromide attaches to the activated carbon of the absorptionbed cartridge 40 prior to discharge of the fumigant/gas mixture from thefumigation apparatus. The absorption bed cartridge 40 is periodicallywashed with a scrubbing solution, such as sodium thiosulphate. In thisembodiment, scrubbing of contents of the absorption bed cartridge 40with sodium thiosulphate yields bromide and sodium methylthiosulphatewhich are non-toxic salts which can be discharged safely to theenvironment. Thus, the methyl bromide gas is degraded following itsfumigation and then extraction from the fumigation apparatus.

The methyl bromide, or other fumigant, absorbed onto the bed cartridge40, may be further processed. For example, the cartridge may beincinerated at a temperature that destroys the fumigant. Methyl bromide,for example, is destroyed at temperatures in excess of 1000° C., such as1100° C. Incinerating the cartridge and the fumigant absorbed thereto atthis or any other appropriate temperature would destroy the methylbromide. Alternatively, the fumigant absorbed onto the absorption bedcan be deabsorbed from it for one or more of recycling, further use as afumigant such as in fumigating other fumigation chambers or shippingcontainers, cleansing, purifying, or shipping back to an authority, forexample, for destruction or processing of any suitable type. Thedesorption may be achieved thermally, that is thermal desorption, forexample, by raising the temperature of the absorption bed to between 60°C. and 80° C. which drives the methyl bromide from the carbon. In thecase of other fumigants a different temperature range may be requiredand a suitable temperature would thus be used.

The desorbed and recovered fumigant gas may be recycled into anothercontainer for fumigation of a like or even unlike cargo as appropriate.The gas may have impurities from the pervious cargo, for exampleimpurities from timber if that is the cargo, however if the recycled gaswas again used on the same cargo type, such as timber, this may notpresent a problem. In some circumstances, the impurities may not be ofany consequence and the gas can be recycled amongst any number of cargotypes.

Alternatively, the absorption bed and the fumigant absorbed thereto maybe disposed of in, for example, land fill.

In some embodiments, the methyl bromide or other fumigant may bedestroyed through a chemical process, such as oxidization for example.The extracted fumigant may be bubbled through water together with ozonegas. The ozone produces hydroxyl radicals in the water that destroys themethyl bromide absorbed into the water. Hydroxyl ions may be producedthrough other means, such as the addition of sodium hydroxide to thewater, for example. The residue in the water can then be disposed of,possibly after its concentration.

In further embodiments of the invention, the fumigant gas used can be ofdifferent types, depending on the fumigation situation. For example, itis within the scope of the invention for gases such as phosphine,sulfural fluoride or carbon dioxide to be used in the fumigation method.In the case of phosphine, passing the gas through an absorptioncartridge of moist carbon causes the gas to be converted to formphosphoric acid on the outside surface of the carbon; this acid can besubsequently washed away from the carbon. In the case of sulfuralfluoride, passing the gas through an absorption cartridge containingcalcium carbonate, or other carbonates or sulphates, causes the gas tobe converted to form various salts which again can be safely disposedof. If carbon dioxide is used as a fumigant to suffocate pests etc, itmay simply be removed from the fumigation chamber by bubbling into avessel or cartridge containing water to form carbonic acid, andsubsequently discarded.

The present invention teaches the removal of the fumigant gases byextraction from the fumigation chamber followed by chemical absorptionof that fumigant so that substantially no fumigant (or fumigantby-product) is expelled to the atmosphere. There are significantenvironmental and occupational health reasons for this further gasprocessing so that a fumigation process such as the one described may beoperated safely in the vicinity of people or animals or generally inurban areas. The absorption process described in the present applicationrepresents an advancement over the exhaust gas incineration or dilutionprocesses described in the prior art. Fumigation systems such as thiswhich can use fumigation reagents such as methyl bromide safely and in away in which is non-toxic to the environment are of major interestworldwide.

In a further embodiment of the invention, the module can be supplied intwo parts which, when co-joined and connected to the enclosed space todefine a fumigation chamber, enable the use of the fumigation method ofthe invention. In such an embodiment a first part of the moduleincluding a panel with fumigant inlet means operatively coupled theretocan be fitted to an enclosed space. Fumigant gas can be introduced intothe fumigation chamber and the fumigation process initiated. The mixingfan controls and the gas sampling lines and gas flow meter test unit arelocated on the first part of the module. After fumigation has concluded,a second part of the module including the extraction means and theabsorption means can be joined or clipped onto the first part of themodule, in order to facilitate the extraction of the majority offumigant gas from the fumigation chamber and absorption of substantiallyall of the fumigant extracted. This second part of the module caninclude the contra-rotating fan, gas exhaust stack and absorption bedcartridge. The advantage of such a two-part apparatus is that aplurality of adjacent fumigation chambers can be operated at once, witheach chamber being fitted with at least a first part of the module,while being able to share one second part of the module, thus reducingthe overall cost of construction of the modules of the invention. In oneexample, several fumigation chambers fitted with a first part of amodule could be in various stages of completion of a fumigationoperation, and as fumigation finishes in each chamber, the second partof the module can be moved to each fumigation chamber in sequence sothat extraction and absorption of fumigant can occur. While this ishappening, some of the chambers where the steps of fumigation,extraction and absorption have already taken place can be emptied andreloaded with new produce for fumigation. Such a series operation canprovide a more efficient ‘continuous’ fumigation process whileminimizing the capital cost of the equipment used.

Now that several preferred embodiments of the present invention havebeen described in some detail it would be apparent to those skilled inthe art that the fumigation apparatus has at least the followingadvantages over the prior art:

1. The fumigation apparatus is adapted to be positioned on a wall of anyenclosed space and thus is relatively convenient and uncomplicated tofabricate;

2. The fumigation apparatus is relatively effective in fumigatingproduce; and

3. The fumigation apparatus is “environmentally friendly” in itsfumigation and discharge of the fumigant.

Effective fumigation of produce by skilled operators would allow for thesafe treatment of material in situ and may eliminate the possibility ofinsects or vermin escaping into the environment, or being transportedacross the country in contaminated produce. This invention can provide afaster fumigation processing rate than the present technology along withenhanced health, safety and environmental benefits.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. For example, the source of fumigant need not belocated on a mobile vehicle such as a utility truck but may rather bemounted onto the exterior of the module itself. The invention need notbe restricted to methyl bromide as the fumigant but rather extends toany substance which is suitable in fumigating produce and thus killingpests, parasites, insects, or vermin. The invention need not berestricted to the specific shape or constructional features describedand may, for example, not include the exhaust stack.

All such variations and modifications are to be considered within thescope of the present invention the nature of which is to be determinedfrom the foregoing description.

1. A fumigation module for fumigation of a fumigation chamber adapted tocontain produce, the module including: a panel which is adapted to bedirectly mounted and removably positioned in or at an opening of thefumigation chamber; fumigant inlet means operatively coupled to thepanel to allow a flow of a fumigant into the fumigation chamber;extraction means also being operatively coupled to the panel to remove amajority of the fumigant from the fumigation chamber; and absorptionmeans operatively coupled to the extraction means, the absorption meansbeing designed to absorb substantially all of the fumigant extractedfrom the fumigation chamber.
 2. A fumigation assembly including themodule of claim 1 and a fumigation chamber adapted to contain producehaving a rigid support structure.
 3. A fumigation module as claimed inclaim 1 further comprising control means operatively coupled to themodule and arranged to control the flow of fumigant into the fumigationchamber.
 4. A fumigation module as claimed in claim 3 wherein thecontrol means includes a system control box and a system of fumigantdelivery pipes and valves adapted in use to supply fumigant from asupply source to the fumigation chamber.
 5. A fumigation module asclaimed in claim 1, wherein the absorption means comprises an absorptionbed including activated carbon to which at least part of the extractedfumigant attaches.
 6. A fumigation module as claimed in claim 1, whereinthe module is adapted to be attached to a source of the fumigant whichis directly associated with a heating source, the latter used to convertthe fumigant into a gaseous form.
 7. A fumigation module as claimed inclaim 1, wherein the fumigant inlet means is adapted to detachablycouple to a mobile source of the fumigant.
 8. A fumigation module asclaimed in claim 1, wherein the fumigant inlet means includes adispersion pipe system in use located above the contents of thefumigation chamber.
 9. A fumigation module as claimed in claim 1,wherein the panel when positioned in use is secure against the passageof fumigant and is fitted with external locking cam devices.
 10. Afumigation module as claimed in claim 9 wherein the panel whenpositioned in use is secure against the passage of fumigant and gases byan inflatable seal.
 11. A fumigation module as claimed in claim 10wherein the seal can be inflated by means of a compressor fitted to themodule.
 12. A fumigation module as claimed in claim 1, wherein themodule is provided with a plurality of mixing fans adapted to circulatefumigant and gases within the fumigation chamber.
 13. A fumigationmodule as claimed in claim 1, wherein the extraction means includes apipe attached to an orifice located in a lower region of the panel, thepipe being connected in turn to an actuated butterfly valve furtherconnected in turn to a contra-rotating fan adapted to provide suctionfor the extraction of the fumigant.
 14. A fumigation module as claimedin claim 13 wherein the extraction means includes an exhaust stackpositioned vertically above the module, the uppermost terminal of theexhaust stack being fitted with a gas diffuser and appropriate rainguard, and the exhaust stack being arranged to receive the extractedgases which are stripped of fumigant.
 15. A fumigation module as claimedin claim 1, wherein the module is fitted with a plurality of smalldiameter pipes independently connected via an arrangement of taps andconnectors to a fumigant sampling and detection meter unit located atthe module.
 16. A fumigation module as claimed in claim 1, wherein themodule includes a fumigant sampling and detection meter unit and powersupply switches for mixing fans, exhaust fan and valve actuators.
 17. Afumigation module as claimed in claim 1, wherein the module is providedin two portions adapted to be operatively coupled together.
 18. Afumigation module as claimed in claim 17 wherein first portion includesthe fumigant inlet means and a second portion includes the fumigantextraction and absorption means.
 19. A method of fumigating produceincluding the steps of: providing a fumigation module which includes apanel, the panel adapted to removably attach to a fumigation chamber,with fumigant inlet, extraction and absorption means being operativelycoupled to the panel; locating the produce to be fumigated in thefumigation chamber; directly attaching the panel in or at an opening ofthe fumigation chamber; providing a flow of a fumigant to the fumigationchamber via the fumigant inlet means; extracting a majority of thefumigant from the chamber via the fumigant extraction means; andabsorbing substantially all of the extracted fumigant using theabsorption means.
 20. A method of fumigating produce including the stepsof: providing a fumigation apparatus including a first portion of amodule including a panel, the panel adapted to removably attach to afumigation chamber, with fumigant inlet means being operatively coupledto the panel; locating the produce to be fumigated in the fumigationchamber; directly attaching the panel in or at an opening of thefumigation chamber; providing a flow of a fumigant to the fumigationchamber via the fumigant inlet means; providing a second portion of themodule adapted to removably attach to the panel, with fumigantextraction and absorption means being operatively coupled to the secondportion; extracting a majority of the fumigant from the chamber via thefumigant extraction means; and absorbing substantially all of theextracted fumigant using the absorption means.
 21. A method offumigating produce as claimed in claim 19, wherein the fumigantextracted from the chamber is absorbed on an absorption bed.
 22. Amethod of fumigating produce as claimed in claim 20 wherein the fumigantextracted from the chamber is absorbed on an absorption bed.
 23. Amethod of fumigating produce as claimed in claim 21 further comprisingwashing at least part of the absorption bed to remove the absorbedfumigant.
 24. A method of fumigating produce as claimed in claim 19further comprising incinerating at least part of the absorption meansand the fumigant absorbed thereto.
 25. A method of fumigating produce asclaimed in claim 19 further comprising desorbing the fumigant from atleast part of the absorption means.
 26. A method of fumigating produceas claimed in claim 25 further comprising providing the desorbedfumigant to another fumigation chamber.
 27. A method of fumigatingproduce as claimed in claim 19 further comprising disposing of at leastpart of the absorption means and the fumigant absorbed thereto.
 28. Amethod of fumigating produce as claimed in claim 19 further comprisingchemical destruction of the fumigant.